A number of cardiac rhythm management products are available for the use in diagnosis and treatment of various conditions. These may include, for example, subcutaneous, transvenous, or intracardiac therapy devices such as pacemakers, defibrillators and resynchronization devices. Implantable, external and/or wearable cardiac monitors are also available. External or wearable therapy products may include defibrillator vests and external pacemakers, as well as automatic external defibrillators.
In some cardiac rhythm management products, a plurality of sensing electrodes may be provided for use in obtaining cardiac electrical signals for analysis of the patient's cardiac status. Some such products have sufficient sensing electrodes to define more than one sensing vector, with each sensing vector defined by a combination of 2 or more electrodes. With multiple sensing vectors available, some systems may take steps to select a primary sensing vector, as not all sensing vectors may be equally suitable at a given time for a given patient to accurately assess cardiac status. As the patient engages in daily activity, such as exercise or merely changing postures, and comes into proximity with external sources of electromagnetic interference, different vectors may perform differently. If the patient's cardiac state changes by, for example, going from a normal sinus rhythm to experiencing a rate induced bundle branch block, an atrial arrhythmia, or due to other pathologies, and/or changes in medication, different sensing vectors may again provide different signal quality.
New and alternative approaches to the monitoring of cardiac signal quality across one or more sensing vectors are desirable.